Method of processing tempered glass and apparatus of processing tempered glass

ABSTRACT

To provide a method of processing a tempered glass in a simple and appropriate manner while a degree of freedom of processing is secured. Vibration of the processing device is controlled in a feedback fashion such that a vibration amplitude and a vibration frequency of the processing device approach to a target vibration amplitude and a target vibration frequency not to keep them in a range where a value of worsening the quality is generated. Further, a specified sample cycle of 0.3 msec or less in the feedback control is employed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application of U.S. patent application Ser. No.14/414,757, filed on Jan. 14, 2015, which is a 371 of InternationalApplication No. PCT/JP2012/072137, filed on Aug. 31, 2012, the entirecontents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a method of processing a tempered glassand an apparatus of processing the tempered glass.

BACKGROUND ART

A display device such as a mobile terminal, a tablet, a touch panel andPDA (Personal Digital Assistant) generally employs a tempered glasswhich is chemically reinforced. The tempered glass configures a glassbase material and a surface reinforced layer (chemically reinforcedlayer) on its top surface. This configuration enables the tempered glasshaving the thinner thickness while realizing the higher strength againstbending stress and impact.

The processing of the tempered glass having the surface reinforced layerof a certain thickness or more and a certain surface compression stressor more (for example, the thickness of the surface reinforced layer is40 μm or more, and the surface compression stress is 600 MPa or more) isnot easy. Accordingly, a method of processing the tempered glass ofPatent Publication 1 describes the tempered glass having the surfacereinforced layer of 30 μm or less and the surface compression stress of600 MPa or less which is processed by employing a known cutting method(such as laser beam machining). Further, Patent Publication 2 proposes amethod of processing a tempered glass (the thickness of the surfacereinforced layer is 40 μm or more, and the surface compression stress is600 MPa or more) having a surface reinforced layer a part of which isremoved for weakening the processing strength at an expected cuttingposition. Then, in this method, an expected cutting trench is formed andcut by using a laser.

PRIOR TECHNICAL PUBLICATIONS Patent Publications

Patent Publication 1:

-   -   Japanese Patent Publication Gazette No. 2004-83378

Patent Publication 2:

-   -   Japanese Patent Publication Gazette No. 2012-31018

SUMMARY OF INVENTION Problems to be Solved by Invention

However, in Patent Publication 1, only the workability of the temperedglass is attached importance and a further thinning and a furtherstrengthening which are currently required are not satisfied byemploying the method of Patent publication 1.

The formation of the expected cutting trench on the surface reinforcedlayer is essential in Patent publication 2 to increase the number of thesteps, and further the processing on the tempered glass is restrictivebecause the expected cutting trench may be formed only in a linearfashion.

Under these situations, the present inventor pays the attention to amethod of processing a tempered glass in which a processing device isvibrated under the rotation thereof and which has been recognized hardlyapplicable thereto. The present inventor has found the conditions forproperly processing the tempered glass in the above method, thenreaching the present invention.

The preset invention has been made in consideration of the abovematters. A first object thereof is to provide a method of simply andproperly processing a tempered glass which has the increased strength bya surface reinforced layer while a degree of freedom of the processingis secured under the situation that a processing device is vibrated androtated.

A second object thereof is to provide a processing apparatus for atempered glass which employs the above method of processing the temperedglass.

Means of Solving Problems

The present invention for achieving the first object can have theconfiguration of a method of processing a tempered glass having asurface reinforced layer by means of a processing device which isvibrated under the rotation thereof,

the method comprising the steps of:

controlling vibration of the processing device to the tempered glass ina feedback fashion such that a vibration amplitude and a vibrationfrequency of the processing device approach to a target vibrationamplitude and a target vibration frequency, together with setting thetarget vibration amplitude and the target vibration frequency not tokeep them in a range where a value of worsening the quality of thetempered glass is generated, the value changing along thickness of thetempered glass during the processing of the tempered glass; and

employing a sample cycle of 0.3 msec or less in the feedback control.

The present invention for achieving the second object can have theconfiguration of an apparatus of processing a tempered glass having asurface reinforced layer by means of a processing device which isvibrated under the rotation thereof,

the apparatus comprising:

a vibration mechanism vibrating the processing device to the temperedglass;

a vibration adjusting means adjusting the vibration mechanism; and

a control means by which, by controlling the vibration adjusting means,vibration of the processing device to the tempered glass is controlledin a feedback fashion such that a vibration amplitude and a vibrationfrequency of the processing device approach to a target vibrationamplitude and a target vibration frequency, the target vibrationamplitude and the target vibration frequency are not kept in a rangewhere a value of worsening the quality of the tempered glass isgenerated, the value changing along thickness of the tempered glassduring the processing of the tempered glass, and the feedback control isimplemented every sample cycle of 0.3 msec or less.

Effects of Invention

In accordance with the present invention, the non-restrictive processingcan be performed without suffering from the restriction of theprocessing pathway even to the tempered glass having the surfacereinforced layer with the higher strength (specifically, the thicknessof the surface reinforced layer is 40 μm or more, and the surfacecompression stress is 600 MPa or more) because the ultrasonic vibrationprocessing is conducted while the processing device is vibrated underthe rotation thereof.

Basically, on the other hand, the vibration amplitude and the vibrationfrequency of the processing device are allowed to be out of the rangewhere the value of worsening the quality is generated during thevibration of the processing device because the vibration by theprocessing device is conducted such that the vibration amplitude and thevibration frequency of the processing device is controlled to approachto the target vibration amplitude and the target vibration frequency inthe feedback fashion, and that the target vibration amplitude and thetarget vibration frequency is set not to keep them in the range wherethe value of worsening the quality of the tempered glass is generated.Since, further, the feedback control is implemented by the sample cycleof 0.3 msec or less, the readjustment can be conducted in quite a rapidtiming. Even if the vibration amplitude and the vibration frequency ofthe processing device would fall into the range where the value ofworsening the quality of the tempered glass is generated, these valuesin the range can be returned to the target vibration amplitude and atarget vibration frequency (out of the range where the value ofworsening the quality) within the above quite the rapid timing.Accordingly, if slight condition changes such as release of a tensilestress inside of the tempered glass would take place during theprocessing of the tempered glass, the glass can follow such the change,thereby appropriately preventing the generations of the cracks and thechippings in the tempered glass over a specified degree. As its result,the tempered glass can be processed simply and reliably.

Accordingly, even the tempered glass of which strength is increased byincorporating the surface reinforced layer can be processed simply andreliably while the degree of freedom of the processing is secured.

The employment over 0.3 msec as the sample cycle in the feedback controlincreases the possibility of the reduction of processing accuracy of thetempered glass (generations of cracks and the chippings in the temperedglass over the specified degree) because, based on the knowledge thepresent inventor has obtained, the glass cannot follow the stress changein the tempered glass. Accordingly, the sample cycle exceeds 0.3 msec isused.

The preferable vibration amplitude and vibration frequency can beprovided in view of the processing accuracy of the tempered glass basedon the knowledge the present inventor has obtained because the targetvibration amplitude is set in the range from 3 μm to 9 μm and the targetvibration frequency is set in the range from 60 kHz to 64 kHz.

The reasons why the target vibration amplitude is set in the range from3 μm to 9 μm is that the cracks and the chippings over a specifieddegree are generated due to the insufficient processing ability (due tothe increase of the cutting resistance occurring by the remaining of thecutting scrap) under 3 μm and that the possibility of generating thecracks and the chippings over a specified degree in the tempered glassis increased because the tempered glass cannot follow the stress changegenerated therein during the processing over 9 μm.

The preferable number of rotation of the processing device can beobtained in view of processing the tempered glass having the surfacereinforced layer with the higher strength under the above-mentionedvibration conditions based on the knowledge the present inventor hasobtained because the number of rotation of the processing device is setin the range from 2000 rpm to 30000 rpm.

The reasons why the number of rotation of the processing device is setin the range from 2000 rpm to 30000 rpm is that the processing effect tothe tempered glass is insufficient under 2000 rpm and that theprocessing effect is reduced by the occurrence of a slip phenomenon(reduction of processing resistance) on the processed surface over 30000rpm, thereby generating the problem of durability.

A plurality of the stacked glasses can be obtained at the same time toelevate the production efficiency by cutting the group of the stackedglasses because the tempered glass having the surface reinforced layerincludes the above group of the stacked glasses prepared by stacking aplurality of the tempered glasses.

The invention can include an apparatus of processing a tempered glasshaving a surface reinforced layer by means of a processing device whichis vibrated under the rotation thereof, the apparatus comprising; avibration mechanism vibrating the processing device to the temperedglass; a vibration adjusting means adjusting the vibration mechanism;and a control means by which, by controlling the vibration adjustingmeans, vibration of the processing device to the tempered glass iscontrolled in a feedback fashion such that a vibration amplitude and avibration frequency of the processing device approach to a targetvibration amplitude and a target vibration frequency, the targetvibration amplitude and the target vibration frequency are not kept in arange where a value of worsening the quality of the tempered glass isgenerated, the value changing along thickness of the tempered glassduring the processing of the tempered glass, and the feedback control isimplemented every sample cycle of 0.3 msec or less. In accordance withthis invention, the non-restrictive processing can be performed withoutsuffering from the restriction of the processing pathway even to thetempered glass having the surface reinforced layer (specifically, thethickness of the surface reinforced layer is 40 μm or more, and thesurface compression stress is 600 MPa or more) by conducting theultrasonic vibration processing in which the processing device isvibrated under the rotation thereof.

The apparatus of processing the tempered glass which may employ themethod of processing the tempered glass can be provided because thetarget vibration amplitude is set in the range from 3 μm to 9 μm and thetarget vibration frequency is set in the range from 60 kHz to 64 kHz inthe control means.

The apparatus of processing the tempered glass which may employ themethod of processing the tempered glass can be provided because thenumber of rotation of the processing device is set in the range from2000 rpm to 30000 rpm in the control means.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] An explanatory drawing showing the tempered glass having thesurface reinforced layer.

[FIG. 2] An entire drawing showing the ultrasonic vibration processingapparatus in accordance with the Embodiment.

[FIG. 3] A diagram showing the controlling relation of the ultrasonicvibration processing apparatus in accordance with the Embodiment.

[FIG. 4] Tables showing the experiment results (the experiment resultsof Processing Experiment 1) wherein the target vibration frequencies ofthe processing device were changed while the conditions were fixed suchthat the target vibration amplitude of the processing device was 8 μmand the sample cycle (response speed) of the feedback was 0.2 msec.

[FIG. 5] Table showing the experiment results (the experiment results ofProcessing Experiment 2) wherein the target vibration amplitudes of theprocessing device were changed while the conditions were fixed such thatthe target vibration frequency of the processing device was 63 kHz andthe sample cycle (response speed) of the feedback was 0.2 msec.

[FIG. 6] Table showing the experiment results (the experiment results ofProcessing Experiment 3) wherein the sample cycles (response speed) ofthe feedback were changed while the conditions were fixed such that thetarget vibration amplitude of the processing device was 8 μm and thetarget vibration frequency of the processing device was 63 kHz.

[FIG.7] Graph showing the relation between the sample cycle (responsespeed) of the feedback and the success rate of the processing.

[FIG. 8] Illustration showing the stack of the tempered glasses to beprocessed.

[FIG. 9] Illustration showing the situation where the stack of thetempered glasses is placed on the fixing base.

[FIG. 10] Illustration showing the situation where the stack of thetempered glasses is cut out.

[FIG. 11] Illustration showing the formation of long apertures andsquare apertures in the stacked block.

[FIG. 12] Illustration showing the polish processing to thecircumferential surface of the stacked block.

[FIG. 13] Illustration showing the protection glass for the portableterminal.

[FIG. 14] Magnified photograph showing the part A of FIG. 13(magnification: 270 times).

[FIG. 15] Magnified photograph showing the part B of FIG. 13(magnification: 270 times).

[FIG. 16] Magnified photograph showing the part C of FIG. 13(magnification: 270 times).

[FIG. 17] Magnified photograph showing the part D of FIG. 13(magnification: 270 times).

[FIG. 18] Magnified photograph showing the part E of FIG. 13(magnification: 270 times).

[FIG. 19] Magnified photograph showing the part of the protection glassfor the portable terminal of Comparative Example which corresponds tothe part A of FIG. 13 (magnification: 270 times).

[FIG. 20] Magnified photograph showing the part of the protection glassfor the portable terminal of Comparative Example which corresponds tothe part B of FIG. 13 (magnification: 270 times).

[FIG. 21] Magnified photograph showing the part of the protection glassfor the portable terminal of Comparative Example which corresponds tothe part C of FIG. 13 (magnification: 270 times).

[FIG. 22] Magnified photograph showing the part of the protection glassfor the portable terminal of Comparative Example which corresponds tothe part D of FIG. 13 (magnification: 90 times).

EMBODIMENTS FOR IMPLEMENTING INVENTION

Embodiments of the present invention will be hereinafter describedreferring to the annexed drawings.

1. Firstly, before the description of the method of processing thetempered glass, the tempered glass which is the subject of the method ofprocessing and the apparatus of the ultrasonic vibration processingacting as the apparatus for processing the tempered glass employing theabove processing method will be described.

(1) Tempered Glass

As shown in FIG. 1, the tempered glass 1 has the configuration includinga glass mother material 2 (for example, alumino-silicate glass) and asurface reinforced layer (chemically reinforced layer) 3 placed on itstop surface side (bottom surface side). The surface reinforced layer 3enables the thinning of the tempered glass 1 and secures the highstrength against the impact. The specific tempered glass 1 to beprocessed has the thickness (δ1) of the mother material 2 of about 0.7mm, the thickness (δ2) of the surface reinforced layer 3 of 40 μm ormore (the surface reinforced layer having the thickness of 70 μm iscurrently developed which is, of course, a subject of the processing),and a surface compression stress from 600 MPa to 700 MPa. Of course, theordinary glass in addition to the tempered glass is a subject of theprocessing by the ultrasonic vibration processing apparatus.

(2) Ultrasonic Vibration Processing Apparatus

(i) As shown in FIG. 2, the ultrasonic vibration processing apparatus 4includes a processing apparatus main body 5.

As shown in FIG. 2, the processing apparatus main body 5 includes arelatively long and cylindrical housing 6 with a closed end, a vibrationapparatus (vibration mechanism) 7 mounted in the housing 6, a processingdevice 8 attached to the vibration apparatus 7, and a motor 9 forrotating and driving the vibration apparatus 7.

(a) The housing is mounted to an elevating apparatus (only part of which(an attaching part to the housing) is shown in FIG. 2) 10. The elevatingapparatus 10 has functions of not only raising and lowering the housing6 along the vertical direction but also adjusting the elevating speed(refer to an arrow). The housing is lowered at a specified setting speed(feed speed) during the processing.

(b) The vibration apparatus 7 includes a columnar body 11, and acolumnar unit 12 for generating ultrasonic vibrations. The body 11 ispositioned, with its axial center oriented along the vertical direction,on the inner circumferential surface of the housing via bearings 13. Thebearings 13 enable the body 11 to rotate around its axial center anddisable the body 11 to move along the direction the axial center extends(vertical direction). A circular cylinder 14 for mounting a driving axis9 a of the motor 9 is formed at the top end of the body 11, and aholding aperture (not shown) is formed at the bottom end surface of thebody 11. The unit 12 for generating ultrasonic vibrations is fixed tothe holding aperture at the bottom surface of the body. As known in theart, the unit 12 is configured with an ultrasonic vibrator, a vibrationtransmitting section and an amplification section connected in series,and these ultrasonic vibrator, vibration transmitting section andamplification section are disposed in this turn from the inside of theholding aperture of the body 11 toward the open side. The ultrasonicvibrator among these has piezoelectric elements and metal blocks forfastening these with bolts, and electrodes are positioned between thepiezoelectric elements and between the piezoelectric element and themetal block. The application of a direct pulse voltage between theelectrodes excites the piezoelectric elements to generate the verticalvibrations. The ultrasonic vibrator generates the strong ultrasonicvibrations by means of a resonance phenomenon when the frequency of thedirect pulse voltage to be applied is set to be equal to the resonancefrequency of the ultrasonic vibrator. The vibration transmitting sectionhas a function of transmitting the vibrations of the ultrasonic vibratorto the amplification section, and the amplification section has afunction of amplifying the vibrations transmitted from the vibrationtransmitting section.

(c) As shown in FIG. 2, the processing device 8 is connected to theamplification section of the unit 12 at the axial center thereof inorder to be vibrated by the vibrations of the unit 12. The processingunit 8 processes the tempered glass under the direct contact therewithand is made of a diamond grind stone in the form of axis, and extendsdownward from the unit 12. The processing device 8 has functions of notonly processing the tempered glass and of but also acting as a sensorfor detecting the pressure change of the tempered glass.

(d) The motor 9 is mounted to an outer surface (top end surface) of thebottom part 6 a of the housing 6. A penetration aperture 15 is formedthrough the bottom part 6 a of the housing 6, which communicates theoutside and the inside of the housing, and the driving axis 9 a of themotor 9 penetrates the penetration aperture 15 and is engaged and held(fixed) to the circular cylinder 14 of the body 11. Thereby, the drivingforce of the motor 9 is transmitted through the body 11 and the unit 12to the processing unit 8 where the processing unit 8 can rotate aroundthe axial center.

(ii) As shown in FIG. 2 and FIG. 3, the ultrasonic vibration processingapparatus 4 includes an ultrasonic oscillator (vibration adjustingmeans) 16 adjusting the vibration amplitude and the vibration frequencyof the unit 12.

The ultrasonic oscillator 16 adjusts an input electric signal(specifically, voltage or current), and the adjusted electric signal isthen supplied to the unit 12 (ultrasonic vibrator). In this

Embodiment, the amplitude and the frequency of an input voltage from apower source are adjusted while the value of current is not changed (forexample, a specified value from 1 to 2 A), and the adjusted voltagesignal (for example, 300 to 400 V) is supplied to the unit 12(ultrasonic vibrator). Of course, in this case, a current signal may besupplied to the ultrasonic vibrator under the constant voltage insteadof the voltage signal.

(ii) As shown in FIG. 2 and FIG. 3, the ultrasonic vibration processingapparatus 4 includes a control unit U which controls the ultrasonicoscillator 16 (unit 12 for generating ultrasonic vibrations).

(a) The voltage signal (amplitude and frequency signals of the voltage)from the ultrasonic oscillator 16, and the rotation number signal of themotor 9 (voltage) are input to the control unit U, and control signalsfor the ultrasonic oscillator 16 and the motor 9 are output from thecontrol unit U.

(b) The control unit U includes a setup section (setup means) whichsetups a target value for a feedback control, a judgment section(judgment means) which judges an operation variable based on thedeviation between the target value of the setup section and the controlvariable, and an execution section (execution means) which outputs thecontrol signal for performing the operation variable coming from thejudgment section.

The target vibration amplitude and the target vibration frequency withrespect to the input voltage to the unit 12 for generating ultrasonicvibrations (ultrasonic vibrator) as the target values for the feedbackcontrol are established in the setup section, and these values changealong thickness of the tempered glass during the processing of thetempered glass, and do not belong to the range where the value ofworsening the quality of the tempered glass is generated (values ofgenerating cracks and the chippings in the tempered glass over thespecified degree). This is because the stress change in the temperedglass during the processing such as release of a tensile stress insideof the tempered glass must be considered. The target current is setupwith respect to the input current to the motor 9 in view of realizingthe effective rotation for the processing.

The target vibration amplitude of the input voltage with respect to theunit 12 for generating ultrasonic vibrations is setup such that thevibration amplitude of the processing device 8 finally falls into arange (which does not fall into a range where a value of worsening thequality of the tempered glass is generated) of 3 μm to 9 μm (preferably8 μm). The values under 3 μm and over 9 μm are recognized to fall in therange where the value of worsening the quality of the tempered glass isgenerated. The reasons why the target vibration amplitude is, based onthe knowledge the present inventor has obtained, set in the range from 3μm to 9 μm is that the cracks and the chippings over a specified degreeare generated due to the insufficient processing ability (due to theincrease of the cutting resistance occurring by the remaining of thecutting scrap) under 3 μm and that the possibility of generating thecracks and the chippings over a specified degree in the tempered glassis increased because the tempered glass cannot follow the stress changegenerated therein during the processing over 9 μm.

The target vibration frequency of the input voltage with respect to theunit 12 for generating ultrasonic vibrations (ultrasonic vibrator) issetup such that the vibration frequency of the processing device 8finally falls into a range (which does not fall into a range where thevalue of worsening the quality of the tempered glass is generated) of 60kHz to 64 kHz (preferably 63 kHz). The values under 60 kHz and over 64kHz are recognized to fall in the range where the value of worsening thequality of the tempered glass is generated. The reasons why the targetvibration frequency is, based on the knowledge the present inventor hasobtained, set in the range from 60 kHz to 64 kHz is that the cracks andthe chippings over specified degrees are generated due to theinsufficient processing ability under 60 kHz and that the possibility ofgenerating the cracks and the chippings over specified degrees in thetempered glass is increased because the tempered glass cannot follow thestress change generated therein during the processing over 64 kHz.

The target current with respect to the motor 9 is established such thatthe rotation number of the processing device 8 falls in a specifiedrotation number from 2000 rpm to 30000 rpm (preferably 5000 rpm). Thereasons why the rotation number of the processing device is set in therange from 2000 rpm to 30000 rpm are that the processing effect to thetempered glass is insufficient under 2000 rpm and that the processingeffect is reduced by the occurrence of a slip phenomenon (reduction ofprocessing resistance) on the processed surface over 30000 rpm, therebygenerating the problem of durability.

In FIG. 3, a numeral 18 denotes a section of inputting a setup valueinto the setup section.

The judgment section judges, with respect of the vibration amplitude ofthe processing unit 8, the operation variable based on the deviationbetween the amplitude of the voltage (return voltage) from theultrasonic oscillator 16 and the target amplitude of the setup section,and judges, with respect of the vibration number of the processingdevice 8, the operation variable based on the deviation between thefrequency of the voltage (return voltage) from the ultrasonic oscillator16 and the target frequency of the setup section. With respect to therotation number of the processing device 8, the operation variable isjudged based on the deviation between the current signal from the motor9 and the target current of the setup section.

The execution section outputs, as the control signals, the respectiveoperation variables from the judgment section to the ultrasonicoscillator 16 and the motor 9. Thereby, the output voltage (amplitude,frequency) from the ultrasonic oscillator 16 is adjusted so that theprocessing device 8 is controlled in the feedback fashion to take aspecified vertical amplitude and a specified frequency. Also, therotation number of the motor 9 is controlled in the feedback fashion tokeep the rotation number of the processing device at a specifiedrotation number.

The control unit is set to perform the feedback control at the samplecycle (response speed) range of 0.3 msec or less or from 0.3 msec to 0.2msec (preferably 0.2 msec). The reasons why the sample cycle is set inthe range of 0.3 msec to 0.2 msec is that the possibility of generatingthe cracks and the chipping in the tempered glass over the specifieddegree increases because the glass cannot follow the slight stresschange therein over 0.3 msec, based on the knowledge the presentinventor has obtained. The lower limit of 0.2 msec is the lowermostlimit currently available, and the feedback control cannot be conductedbelow the above lower limit sample cycle. If a tempered glass having asample cycle below 0.3 msec will be developed, the use thereof is morepreferable.

The speed-up of the analogue/digital conversion function and thearithmetic processing ability of CPU in the control unit U is intendedcompared to an existing control unit for the speed-up of the samplecycle of the feedback control. Thereby, when the sample cycle is set tobe 0.2 msec and the vibration number (frequency) of the processingdevice 8 is set to be 80 kHz specifically, the number of the vibrationimpact supplied to the tempered glass before the vibration startsresponding to the load change under the optimum conditions can besuppressed to 16 times. When the vibration conditions are made optimumat the sample cycle of 0.2 msec under the feed speed of the processingdevice 8 of 30 mm/min., the processing proceeds with the feedbackcontrol taking place every 0.1 μm so that the slight condition change(stress change) during the processing can be responded (followed).

On the other hand, when the vibration number (frequency) of theprocessing device 8 is 80 kHz, the vibration impact is supplied to thetempered glass once in every 0.0000125 second (0.0125 ms). When thesample cycle (vibration response speed) is 10 msec under the samevibration number (under the case of existing control unit), 800 times ofthe vibration impacts are supplied to the tempered glass before thevibration starts responding to the load change under the optimumconditions.

When the vibration conditions are optimized at the sample cycle of 10msec under the feed speed of the processing device 8 of 30 mm/min, theprocessing proceeds every 5 μm. This 5 μm is relatively larger withrespect to the surface reinforced layer of several tens μm, and thecondition changes of the tempered glass cannot be followed. As itsresult, the processing must be performed while the stress is given tothe tempered glass, and the cracks are generated on the tempered glass.

(iv) Target Values of Control

The target values of the above control will be backed up in theProcessing Experiments 1 to 3 below which have been conducted by thepresent inventor. The Processing Experiments 1 to 3 were conducted tothe tempered glass under the following common experiment conditions, andtheir evaluations were performed based on the following evaluationstandards.

(a) Common Experiment Conditions

Tempered Glass to be Processed

Material of mother material: alumino-silicate glass

Thickness of mother material (δ1): 0.70 mm

Thickness of surface reinforced layer (δ2): 40 μm (0.04 mm)

Compressive residual stress: 600 MPa to 700 MPa

Processing Device 8

Feed speed for processing: 60 mm/min.

Number of rotations: 5000 rpm

Diameter of axial processing device: i.5 mm

Grain size of processing device 8: #600

(b) Common Evaluation Standard

×: Tempered glass was broken.

Δ: Chipping 100 to 150 μm (processing might be possible, but quality wasworse)

◯: Chipping 30 μm or less (both of processing and quality were good)

(c) Processing Experiment 1

(c-1) An experiment was conducted in which a target number of vibration(target frequency) was changed under the fixed conditions below byadjusting voltages for obtaining excellent number of vibrations of aprocessing device 8 with respect to one piece of tempered glass.

Target vibration amplitude of processing device: 8 μm

Sample cycle (response speed) of feedback: 0.2 msec

(c-2) The results shown in FIG. 4 were obtained by ProcessingExperiment 1. In accordance with the results of FIG. 4, it was found outthat the target number of vibration of the processing device 8 waspreferably from 60 kHz to 64 kHz (especially 64 kHz) (the range wherethe value of worsening the quality is under 60 kHz and over 64 kHz).

(d) Processing Experiment 2

(d-1) An experiment was conducted in which a target vibration amplitudeof a processing device 8 was changed under the fixed conditions below byadjusting voltages for obtaining excellent target vibration number ofthe processing device 8 with respect to one piece of tempered glass.

Target frequency of processing device: 63 kHz

Sample cycle (response speed) of feedback: 0.2 msec

(d-2) The results shown in FIG. 5 were obtained by Processing Experiment2. In accordance with the results of FIG. 5, it was found out thatvibration amplitude of the processing device 8 was preferably from 3 μmto 9 μm (especially 8 μm) (the range where the value of worsening thequality is under 3 μm and over 9 μm).

(e) Processing Experiment 3

(e-1) An experiment was conducted in which a sample cycle (responsespeed) of feedback was changed under the fixed conditions below becausethe sample cycle of the feedback of the processing was important for thetempered glass in which a slight condition change occurred during theprocessing.

Target vibration amplitude of processing device: 8 μm

Target vibration frequency of processing device: 63 kHz

(e-2) The results shown in FIG. 6 were obtained by ProcessingExperiment 1. In accordance with the results of FIG. 6, it was found outthat the sample cycle of the feedback was preferably under 0.3 msec(especially 0.2 msec). The lower limit (0.2 nsec) is a limit valuecurrently available

(e3) FIG. 7 shows the relation between the sample cycles (responsespeeds) of feedback control and the success rates of the processing. Inaccordance with FIG. 7, it was found out that the success rate increasedwith the decrease of the response speed, and the success rate increasedwith the significant rise especially below 0.5 msec. The evaluation ofprocessing success was the same as the above-mentioned (◯). In FIG. 6,the results with the success rate of 87% or more are evaluated as “◯”.

Then, an example of the method of processing the tempered glass inaccordance with Embodiment will be described together with the controlof the above control unit U.

(1) At first, as shown in FIG. 8, the tempered glass 1 (thickness ofmother material was 0.7 mm, thickness of surface reinforced layer was 40μm or more, and surface compression stress was 600 MPa or more) havingthe surface reinforced layer 3 in the shape of a larger plate isprovided. The larger plated-tempered glass is cut out for preparing aplurality of pieces having a certain shape which is used for protectionglass of portable terminals and tablets. In the present Embodiment, astack (a group of stacked glasses) 1A which is prepared by joining aplurality (for example, 12 sheets) of larger plates (tempered glass 1)stacked together by using an adhesive 20 (adhesive layer is 80 μm to 100μm) is provided for elevating the production efficiency. The adhesive 20preferably includes a UV cure adhesive which is cured with ultravioletrays and soluble in warm water because the adhesive is required to berapidly cured and thereafter to be peeled off from the cut-outrespective pieces of the tempered glass. The glass 1 n forming theoutermost surface (top surface, bottom surface) of the stack 1A may beinexpensive ordinary glass instead of the tempered glass becausechipping likely occurs in the outermost surface of the stack 1A. Anotherstack 1A prepared by joining 16 sheets of larger plates (tempered glass1) of which a mother material thickness is 0.5 mm may be also employed.

(2) As shown in FIG. 9, the above stack 1A is then placed on a thickfixing base 21. A plurality of trenches (not shown) are formed on a topsurface of the fixing base 21, and a plurality of communicationapertures 22 which are communicated to the respective trenches throughthe inside of the fixing base 21 are open to a side surface of thefixing base 21. A suction device (not shown) is connected to therespective communication apertures 22, and air above the fixing base 21is sucked through the trenches on the top surface of the fixed base 21and the communication apertures 22. Thereby, the stack 1A placed on thefixing base 21 is fixed on the fixing base 21 by means of the suckingaction.

(3) As shown in FIG. 10, grind processing is performed, by employing theabove-mentioned ultrasonic vibration processing apparatus 4, for cuttingout a plurality of pieces (stacked layer block la) having a size forprotection glass of portable terminals and for forming long apertures 23and square apertures 24 in the respective stacked layer blocks 1 a asshown in FIG. 11. After the cut-out of the stacked layer blocks 1 a fromthe stack 1A, which removes all except for the stacked layer blocks lafrom the stack 1A, polish processing for finishing is performed to theperiphery of the respective stacked layer blocks 1 a, the long apertures23 and the square apertures 24. The respective stacked layer blocks 1 aremain fixed on the fixing base 21 based on the sucking action. In FIG.12, as a matter of convenience, the fixing base 21 is scaled down, andthe long apertures 23 and the square apertures 24 formed in the stackedlayer block 1 a are not shown.

The feedback control is conduced in the polish processing and the grindpolishing of the stacked layer block which employs the ultrasonicvibration processing apparatus 4 for bringing the vibration amplitudeand the number of vibrations close to the target vibration amplitude andthe target number of vibrations, respectively. In order to basicallyprevent the occurrence of the cracks and the chippings of the temperedglass even if the stress is slightly changed in the tempered glassduring the processing, the target vibration amplitude and the targetnumber of vibrations are used which are outside of the range where thevalue of worsening the quality of the tempered glass (standard ofgenerating cracks and chipping in the tempered glass over specifieddegrees) is generated, the value changing along the thickness directionof the tempered glass during the processing.

Specifically, the target vibration amplitude of the processing device 8is set in the preferable range from 3 μm to 9 μm, for example, 8 μm, andthe target number of vibrations of the processing device 8 is set in thepreferable range from 60 kHz to 64 kHz, for example, 63 kHz. The reasonswhy the target vibration amplitude of the processing device 8 is set inthe range from 3 μm to 9 μm, and why the target vibration frequency isset in the range from 60 kHz to 64 kHz are mentioned above. The samplecycle of 0.2 msec which is below 0.3 msec is used in the feedbackcontrol in this case for properly preventing the generation of thecracks in the tempered glass by rapidly grasping the stress changeoccurring in the tempered glass and by reducing the stress to thetempered glass.

In this case, the processing device 8 is rotated under the number ofrotations of 5000 rpm which belongs to a range from 2000 rpm to 30000rpm for obtaining preferable effects of the rotation together withsufficiently producing the effects of the ultrasonic vibrationprocessing. The other processing conditions are those ordinarilyemployed.

Then, after the polish processing, the stacked layer block 1 a issubjected to the chemical treatment for strengthening the glass endsurface by using hydrofluoric acid. Then, the block 1 a is dipped intowarm water, and the respective tempered glasses 1 are peeled off.Thereby, the processed tempered glass can be obtained as a final product(such as protection glass for portable terminal).

EXAMPLES

3. The quality of the test glass prepared by employing the presentmethod (above processing apparatus) and the quality of another testglass of Comparative Example prepared by employing the prior art methodwere compared with each other and evaluated.

(1) In Case of Test Glass Prepared by Employing the Present Method

(i) Preparation of Test Glass

Preparation of protection glass 1P for portable terminals acting as thetest glass and shown in FIG. 13 was attempted.

(ii) Specific Method of Preparing Test Glass of Present Method andConditions Thereof

A method of preparing the test glass is the same as the method ofprocessing the above tempered glass. That is, 12 sheets of the temperedglass (mother material was alumino-cilicate glass, thickness of mothermaterial was 0.7 mm, thickness of surface reinforced layer was 40 μm,and surface compression stress was 600 MPa or more) having the surfacereinforced layer in the shape of a larger plate were stacked and fixedamong one another by using a UV cure adhesive. Pieces (stacked layerblock 1 a) having the same size as that of protection glass of portableterminals were cut out from the stacked sheets. The polish processing(primary processing) of the long apertures 23 and square apertures 24was conducted onto the above cut-out pieces to prepare primarilyprocessed articles (stacks). Then, the finishing processing (secondaryprocessing) onto the primarily processed articles was performed forchamfering the circumferential surface, the long apertures 23 and thesquare apertures 24 to prepare secondarily processed articles (stacks).Then, the polish processing was conducted onto the secondarily processedarticles, and the respective glass plates of the stacked layer block laafter the above processing were dipped into warm water for peeling off,thereby obtaining the test glass (for evaluation).

The above-mentioned ultrasonic vibration processing apparatus 4 wasemployed in the primary processing and the secondary processing, and theconditions thereof are as follows.

Primary Processing Conditions

Processing Device 8

Type: diamond grind stone in form of axis (grain size: #320)

Diameter: 1.5 mm

Feed speed: 60 mm/mm.

Vibration amplitude: 8 μm

Number of vibrations: 63 kHz

Sample cycle (response speed) of feedback control; 0.2 msec

Number of rotations: 5000 rpm

Secondary Processing Conditions

Processing device 8

Type: diamond grind stone in form of axis (grain size:#600)

Diameter: 1.5 mm

Feed speed: 60 mm/min.

Vibration amplitude: 5 μm

Number of vibrations: 63 kHz

Sample cycle (response speed) of feedback control; 0.2 msec

Number of rotations: 5000 rpm

(iii) Method of Evaluating Test Glass Prepared by Present Method andResults of Evaluation

The processed conditions after the primary processing, after thesecondary processing and after the polish processing of the respectiveparts A to E of the test glasses shown in FIG. 13 were examined.

As apparent from magnified photographs shown in FIG. 14 to FIG. 18 (270times), the respective parts A to E of the test glass exhibited theexcellent processed states in each of the processing stages (after theprimary processing, after the secondary processing and after the polishprocessing).

(2) In Case of Test Glass Prepared by Employing Prior Art Method

(i) Preparation of Test Glass

Similarly to the case of the test glass prepared by the present method,the preparation of protection glass for portable terminals acting as thetest glass shown in FIG. 13 was attempted.

(ii) Specific Method of Preparing Test Glass by Prior Art Method andConditions Thereof

Similarly to the preparation of the present method, the stack consistingof 12 sheets in the shape of larger plates (the tempered glass havingthe surface reinforced layer) adhered among one another was prepared,and the primary processing (cut-out of the stacked layer block 1 a, andprocessing of the long apertures 23 and square apertures 24) onto thestack under the primary processing conditions below was tried. However,a plurality of cracks were generated after the cut-out of the stackedlayer block 1 and in the early stage of processing the long apertures 23during the primary processing. Accordingly, the subsequent processingincluding the processing of the square apertures 24 in the primaryprocessing was abandoned for the parts (refer to part D and part E inFIG. 13) regarding the aperture processing of the test glass ofComparative Example. Although the secondary processing and the polishprocessing were conducted onto the part B and the part C among the partswith respect to the circumferential surface (refer to part A to part Cin FIG. 13) of the test glass of Comparative Example, the subsequentprocessing of part A was abandoned because of the crack generation.

Primary Processing Conditions

Processing Device 8

Type: diamond grind stone in form of axis (grain size: #320)

Diameter: 1.5 mm

Feed speed: 60 mm/min.

Vibration amplitude: 8 μm

Number of vibrations: 50 kHz

Sample cycle (response speed) of feedback control; 10 msec

Number of rotations: 5000 rpm

(iii) Method of Evaluating Test Glass of Comparative Example and Resultsof Evaluation

Examination of the processed conditions after the primary processing ofthe respective parts A to D (refer to FIG. 13) of the test glass ofComparative Example provided magnified photographs of FIG. 19 to FIG. 21(270 times) and of FIG. 22 (90 times). Cracks or chippings over aspecified degree were generated at the respective parts A to C of thetest glass of Comparative Example, and a plurality of larger cracks weregenerated at the part D so that the quality thereof was too bad to besupplied as a finished article. A larger central aperture in FIG. 22 wasmade during the initial stage before the formation of the long apertures23.

DESCRIPTION OF SYMBOLS

1 . . . tempered glass

1A . . . stack (group of stacked glasses)

1 a . . . stacked layer block (group of stacked glasses)

3 . . . surface reinforced layer

4 . . . ultrasonic vibration processing apparatus

7 . . . vibration apparatus (vibration mechanism)

8 . . . processing device

9 . . . motor (rotation power source)

16 . . . ultrasonic oscillator (vibration adjusting means)

U . . . control unit (control means)

What is claimed is;:
 1. An apparatus of processing a chemical temperedglass having a surface reinforced layer by means of a processing devicewhich is vibrated under rotation thereof, the apparatus comprising; avibration mechanism vibrating the processing device to the chemicaltempered glass; a vibration adjusting means adjusting the vibrationmechanism; and a control means by which, by controlling the vibrationadjusting means, vibration of the processing device to the chemicaltempered glass is controlled in a feedback fashion such that a vibrationamplitude and a vibration frequency of the processing device approach toa target vibration amplitude and a target vibration frequency, thetarget vibration amplitude and the target vibration frequency are notkept in a range where a value of worsening the quality of the chemicaltempered glass is generated, the value changing along thickness of thechemical tempered glass during the processing of the chemical temperedglass, and the feedback control is implemented every sample cycle of 0.3msec or less.
 2. The apparatus of processing the tempered glass asclaimed in claim 1, wherein the target vibration amplitude is set in arange from 3 μm to 9 μm and the target vibration frequency is set in arange from 60 kHz to 64 kHz in the above control means.
 3. The apparatusof processing the tempered glass as claimed in claim 1, wherein thenumber of rotation of the processing device in the control means is setin a range from 2000 rpm to 30000 rpm.